Variable time delay reefing line cutter



Oct. 29, 1968 M. s. KRIESEL.

VARIABLE TIME DELAY REEFING LINE CUTTER -Sheet 1 l-VVENTOR. MA RSHALL S.KKIESEL 2 Sheets Filed Oct. 24, 1967 lrromvty:

1968 M. s. KRIESEL.

VARIABLE TIME DELAY REEFING LINE CUTTER 2 Sheets-Sheet 2 Filed Oct. 24,1967 INVENTOR. MA RSHALL I. KRMSEL drum/Er:

United States atent 3,408,026 VARIABLE TIME DELAY REEFING LINE CUTTERMarshall S. Kriesel, St. Paul, Minn., assignor to Aerospace SystemsCompany, Minneapoiis, Millm, a corporation of California Filed Oct. 24,1967, Ser. No. 677,591 9 Claims. (Cl. 244-152) ABSTRACT OF THEDISCLOSURE A reefing line cutter for use with cargo carrying parachuteshaving actuation means which will delay the time of actuation of thereefing line cutter, and consequently delays the time when the reefingline is cut after actuation so that the reefing line will not be cutuntil the load is proximate the ground after being dropped by aircraft.The cutter has actuating means including a replaceable time delayelement. The time delay element can be changed. The element used isfired automatically upon ejection of the cargo carrying parachute andwill actuate the reefing line cutter after a preselected length of time.The replaceable element is mounted onto the end of a long, flexibleleader made of a pyrotechnic line covered with elastomeric materialwhich is of length to protrude outside the folded cargo parachute sothat the time delay element can be changed in flight if conditionschange.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates to variable time delay actuation means used specifically withreefing line cutters for cutting a reefing line on cargo carryingparachutes.

The prior art Reefing line cutters presently in use are generallyactuated by the sending of an electrical impulse through conductors tothe cutter located on the parachute so that the reefing line cutter willbe energized after the cargo chute has cleared the aircraft. However,with the electrical actuation, the problems arising from brokenconductors, shorting of the system, and the need for actuation of thecutter before it leaves, at the time it leaves or shortly after it hasleft the aircraft, limit the applicability of this type of system. Whenthe cargo is dropped from a substantial altitude and the reefing line iscut as soon as the parachute leaves the aircraft, the full parachute issubjected to wind in its fully unfurled condition for a greater lengthof time. This makes accuracy of the drop harder to obtain. Further, theuse of electric initiation for reefing line cutters makes the unitsomewhat sensitive to static electricity, radio frequency straycurrents, and also there are elaborate ground check out procedures forthe circuits before the chutes were loaded. The check out procedurerequired electrical checking equipment as well.

SUMMARY OF THE INVENTION The present invention consists of an ordinanceactuated reefing line cutter with integral impulse transmission lineattached and an insertable time delay ignition element. The ignitionelement can be easily replaced so that the amount of time delay can bechanged as desired. The ignition element is actuated with a standardmilitary firing pin breach assembly acting on a percussion cap thatignites a pyrotechnic compound that in turn will burn at a set rate andwill then actuate a fuse-like ignition assembly to ignite a pressurecartridge used as the prime mover for the reefing line cutter, after thepreselected time.

The transfer from the time delay cartridge to the pressure cartridge isaccomplished by the use of a pyrotechnic material encapsuled in anelastomeric material and which Patented Oct. 29, 1968 'ice can beelongated so that the time delay cartridge extends out of the foldedparachute when the parachute is in place in the aircraft. This meansthat the time delay cartridges can be changed by the crew to meetchanging conditions.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a fragmentary perspectiveview of a cargo having a cargo parachute installed thereon, and showinga replaceable time delay element used with the reefing line cutterextending from the parachute;

FIGURE 2 is a perspective view of a reefing line cutter having thevariable time delay capsule attached thereto in position as it would beprior to cutting the reefing line;

FIGURE 3 shows the reefing line cutter of the present invention as itwould appear in a dropping parachute prior to the time of dereefing thechute; and

FIGURE 4 is an exploded vertical sectional view of the variable timedelay reefing line cutter made according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIGURE 1, there is shown abox of cargo 10 arranged with cargo carrying straps 11 which is used fordropping supplies to persons on the ground from an aircraft. The straps11 are used for tying the cargo together, and load support straps 12 arealso used and these would be attached to the suspension lines 13 of thechute when it is opened.

A parachute 14 which is packed as shown in FIGURE 1, is placed on top ofthe cargo 10. The parachute package has static lines 15 protrudingtherefrom which are used for unfurling the chute when the cargo isejected from the aircraft. The static lines 15 are normally snapped ontoa line or ring in the aircraft and when the cargo is ejected, the chuteis dragged out by the static lines.

A variable time delay reefing line cutter assembly illustrated generallyat 16 is installed within the folded chute as will be more fully shownlater and is mechanically actuated with a variable firing and time delayelement assembly 17. The element assembly is mounted onto the end of aflexible fuse-like line 18 that extends out of the chute package so thatthe quick change assembly of the variable time delay actuator isaccessible to the crew of the aircraft prior to the time the cargo isdropped. The

time delay element assembly 17 has a trigger 21 with a ring 22 attachedthereto. The ring 22 in turn is attached with a cord 23 to the staticline hook up element 24 for the static lines 15. As the static lines arepulled out when the cargo is ejected,'the mechanical trigger 21 will beactuated to energize the time delay assembly and cause eventualdereefing of the parachute by cutting the reefing line. The static linesare hooked to a cable inside the aircraft so that when the load ejectsthe lines are pulled to open the parachute.

Referring specifically to FIGURE 3, the parachute canopy 25, as iscustomary, has canopy loops 26 at the peripheral edge thereof and eachof the canopy loops has a suspension line 13 attached thereto.Suspension lines 13 then attach as at 28 to the support lines 12 for thecargo. While FIGURE 3 is shown in its horizontal direction, it should benoted that the load would be vertically below the canopy and theorientation of the figure was merely for convenience in illustrating it.

A reefing line 27 is passed through the canopy loops and holds thecanopy 25 in a partially reefed condition as shown in solid lines inFIGURE 3 after the parachute has been released and the cargo isdescending. The rate of descent is quite high, because the chute isreefed and in order to slow this rate of descent so the cargo isdeposited gently, the reefing line 27 is cut so that the canopy opens toits fully opened position as shown in dotted lines in FIGURE 3. Thevariable time delay reefing line cutter assembly 16 of thepresentinvent'ion permits the delay of the cutter actuation time as wellas permitting the mechanical actuation of the reefing line cutter.

The cutter assembly itself illustrated generally at includes a body 31having an Opening through which the reefingline cutter passes and anupright member 32 to which a latch 33 is pivotally attached. The latch33 forms a'pocket 34 which will receive the canopy loop 26, and when thelatch is closed as shown in FIGURE '2, the nut 35 is closed down ontothe latch ends and holds the latch in position. The latch 33 includes aslot 36 which is of size to permit'the suspension line 13 to passtherethrough. The suspension line 13 is attached to the canopy loop 26to which the reefing line cutter assembly is also attached; The reefingline cutter body made such as that shown, is shown in greater detail inUs. Patent No. 3,348,793. However, electrical actuation is shown for thereefing line cutter in that patent.

The cutter body, as shown perhaps best in FIGURE 4, houses a guillotinetype cutter 37 which is actuable inside a chamber so that it will movefrom position as shown in FIGURE 4 to a cutting position with thecutting edge 37a against the stop 38. The reefing line 27 at that timewill'have been severed inasmuch as it passes through a cross holethrough the chamber 43 for the cutter 37. The body 31 houses anordinance cartridge 39 which has a charge 42 of explosive compoundtherein. When the explosive compound 42 is ignited, it will formpressure inside the chamber 43 behind the cutter and force the cutteragainst the stop surface 38 to sever the reefing line 27. The ordinancecartridge 39 is threaded into the housing 31. The ordinance cartridge 39has a rearwardly projecting stem 44 on which an elastomeric materialforming elongated line 18 is molded. The nut 35 is mounted over theelastomeric material and threadably engages external threads on the stem44 so that it can be threaded down against the latch 33 to hold thelatch in place.

The line 18 is held in place with suitable grooves on the stem and iselongated as shown a sufiicient distance so that it will protrudeoutside a folded parachute package. In the interior of the line 18 thereis a fuse-like pyrotechnic line 45 which will burn when ignited at acontrolled rate and will eventually ignite and cause the charge 42 toburn. The pyrotechnic line is thus completely encased in the elastomericmaterial 46 forming line 18. 'In an outer end portion 47 of the line 18is enlarged to encompass and mount a mounting member 48. Mounting member48.is covered with the elastomeric material as well and forms anintegral assembly. The mounting member 48 is cylindrical member havingan interior chamber 51. The mounting member. 48 has a charge ofpyrotechnic material 52 at the inner end thereof and the pyrotechnicline 45 is embedded in this charge. The charge 52 is open to theinterior chamber 51. The line 45 is made and sold by McCormick Selph/ ATeledyne Company, Hollister, Calif.

A variable time delay quick change unit 17 includes a main body 53 whichis of size to slide within chamber 51. The body 53 has a collar 54rotatably mounted thereon at the outer end thereof. The collar 54 isspaced from the outer surface of the body itself so that there is achamber into which the mounting member 48 will slide. The collar 54locks onto small lock knobs 55 to hold the assembly 17 in place in themounting member. This is a quick change lock which can either be partialtwist as shown (it can also have pin grooves inside the collar like abayonet lamp base socket), or a snap lock with small spring loaded lugssuch as 55, or any other quick change arrangement. The protrudingportion 56 of the body 53 is of larger size than the main portion of thebody. This section protrudes out from the mounting member 48.

The interior of the main body 53 has a chamber in 4 which a time delayelement 57 is mounted. The time delay element can consist of severalwindings of a linear pyrotechnic line such as that shown at 45 aroundthe central core member 58. The rate of burning of this fuselikepyrotechnic line is known and therefore the length of line necessaryfor'a known time'delay can be found.

One end of the line forming the time delay element 57 is embedded in apercussion cap 61 at the inner end of the assembly and the outer end ofthe line is embedded in a transfer or output charge 62. The outputcharge is of a suitable ignition material which will ignite the pickupcharge 52 after the time delay has been initiated. A spring loadedfiring pin 63 is mounted into an interior chamber 64. The pin 63 has acenter member that extends into a collar 65 at the outer end of the body53 and is slidably mounted and guided therein. A spring 66 is mountedbehind the firing pin head and abuts against an inner end of the chamber64. The firing pin actuator 21 is also mounted into collar 65. Theactuator 21 interlocks as shown at 68 with the outer end of the firingpin, and when both of them are in the collar, they cannot be separated.However, the actuator 21 can be pulled in direction as indicated by thearrow 71 so that interlock portion 68 clears the collar 65. At thattime, the actuator portion will disengage the firing pin and release thepin. It should be noted that by the time the interlock section clearsthe collar, the spring 66 will be compressed a great amount and thefiring pin will be fired at the percussion cap 61 in opposite directionfrom that indicated by arrow 71. This will fire the percussion cap,ignite the time delay element 57 and then the entire unit will beenergized. The ring 22 is actually mounted in the actuator member 21. Across hole 72 extends through the collar portion 65 and aligns with ahole in the actuator section 21 when the unit is in its ready position.The safety pin 73 can be inserted through the cross hole to prevent theactuator member from being pulled out in direction as indicated by arrow71 and prevent accidental firing of the time delay cartridge.

The mounting member 58 for the time delay element 57, as shown, is aspool-like member having two end sections 74, .74 joined together by acenter section 75. The time delay line which is a linear burningpyrotechnic line, can then be wound onto the spool so that it will fitwithin the interior chamber of the housing 53. The length of linedetermines the length of time delay, and this can be accurately madebecause the pyrotechnic line is designed to burn at a predeterminedrate. Thus it is merely a matter of measuring out the amount of linenecessary for a given time delay, winding it onto the spool mountingmember 58, and then placing the assembly with the appropriate percussioncap at one end, and the transfer charge at the other end, and thenmounting the unit inside the housing 53. Likewise, a standard militaryfiring pin 63 can be used with merely the interlock for the actuatorsection 21 made so that the unit will be held in place. When the pin ispulled rearwardly in the interlock made, the actuator section 21 has ashoulder 76 that abuts against the end of the collar 65 to hold the pinfrom firing the charge until the actuator section is released.

The time delays can be made from one second up to five minutes ifdesired, at the present time. The line 45 inside the flexible line 18also serves as a time delay because the burning rate of this line isknown. The flexible line is of sutficient length so that it will extendout from the folded parachute so that the quick change element 17 caneasily be inserted in the mounting member or removed as desired. Allthat is necessary is a visual check to make sure that the time delayelement is in place, and then the ring 22 is fastened to the staticline. When the static-line is pulled, the ring 22 will be pulled movingthis actuator 21 in direction as indicated by arrow 71 until theinterlock section 68 with the firing pin releases causing the firing pinto fire. That is the initiation of the time delay. This happens when theload is dropped,

and the parachute is opened partially as shown in FIG- URE 3. Then afterthe time delay, the reefing line 27 will be cut permitting the canopy 25of the parachute to fully unfurl (as shown in dotted lines in FIGURE 3)and slow the descent of the cargo to the desired speed upon contact.

If the planned flight program is altered or a different cargo extractionaltitude is chosen after the plane is in the air, the crew or loadmasterin the aircraft will remove the original time delay element and replaceit with a different time delay element. The navigator can give thevalues necessary, and a complete a range of time delay elements can beeasily stored on the aircraft itself. Of course, it is obvious that thetime delay elements can be stamped with the amount of time delay orcolor coded if desired. After the elements have been replaced, it ismerely a matter of retying the firing pin actuator 21 to the parachutestatic lines and the cargo can be deployed immediately.

The free movement of the flexible line 18 permits this ease ofinspection and insertion of the time delay elements. Yet, at the sametime, the cutter is positively positioned by looping it under the canopyloop 26 and the associated suspension lines 13. This keeps the reefingline cutter positively positioned so that it will cut whenever it isactuated.

Of course, the safety pin 73 will have to be removed before the load isextracted so that the firing pin will fire.

By permitting the cutting of the reefing line when the cargo is close tothe ground, the trajectory of the load can be more closely calculated sothat even though the load may be dropped from a high altitude, theeffect of wind drift will be minimized. When the chute is dropping in areefed condition, the wind has a lesser effect than when the chute isfully unfurled. Thus the amount of time that the chute is fully unfurledshould be kept to a minimum.

Mechanical actuation gives high reliability performance and safetybecause there is no high explosive detonations. Functionally it iscompletely reliable because the components such as the pyrotechnic line45 can be enclosed in an elastomeric material and completely sealed fromthe weather. The time delay elements also can be stored so that they areuneffected by the ambient conditions and will perform reliably eachtime.

What is claimed is:

1. In a cargo carrying parachute folded into a parachute package beforeuse and having means including a line which, when severed, is operativeto fully depoly the parachute as it drops, and a cutter to cut said lineupon receiving a given signal, the improvement comprising actuationmeans for said cutter including an elongated actuation signal transferelement, said elongated element being operably fastened at a first endto said cutter, said cutter having cutting means, actuating means forsaid cutting means actuable upon receiving an actuation signal, acoupling device at a second end of said elongated element, said couplingdevice having two sections, a first section of said coupling devicebeing fixedly attached to the elongated element and a second section ofsaid coupling device being readily removable from the first section,said second section including an actuation signal initiator and a timedelay element to transfer the initiated actuation signal from the signalinitiator to the elongated actuation signal transfer element, saidsecond section being readily replaceable and removable from said firstsection whereby second sections of different time delays can beinterchanged on said first section.

2. The combination as specified in claim 1 wherein said actuating meansfor said cutter is comprised as a pyrotechnic member, said time delayelement including a burnable pyrotechnic member of predetermined lengthwhich can be changed in different second sections to change the lengthof the time delay.

3. The combination as specified in claim 1 wherein the line comprises areefing line for partially reefing a cargo carrying parachute, saidcutter being attached to said parachute, and said elongated elementextending a sufficient distance so that said coupling device protrudesfrom the parachute package when the cargo carrying parachute is infolded condition.

4. The combination as specified in claim 3 wherein said actuation signalinitiator includes a percussion detonation device, and mechanicalactuator means extending out of said second section for firing saiddetonation device.

5. The combination as specified in claim 2 wherein the second sectionincludes an interior spool mounting member, said pyrotechnic membercomprising said time delay element being wound onto the spool and havingone end in operative communication with said actuation signal initiatorand the other end thereof in operative communication with said elongatedactuation signal transfer element.

6. The combination as specified in claim 4 wherein said mechanicalactuator means comprises a slidable pin, means to connect said slidablepin to a static line of the cargo carrying parachute, said pin actuatingsaid detonation device upon receipt of motion transferred to it when thestatic line of the parachute is pulled.

7. The combination as specified in claim 4 wherein said detonationdevice further includes a linearly slidable firing pin mounted formovement with respect to the second section, interlocking means betweensaid firing pin and said mechanical actuator means, said interlockingmeans being releasable when said mechanical actuator means has movedsufficiently far so the interlocking means clears said second sectionthereby to release said firing pin.

8. The combination as specified in claim 7 and aligning cross holes insaid second section and said mechanical actuator means, and a safety pinadapted to be inserted through said aligning cross holes to preventmovement of said mechanical actuator means when said safety pin is inplace.

9. The combination specified in claim 8 wherein said elongated elementis encased with an elastomeric material substantially unaffected byatmospheric conditions.

References Cited UNITED STATES PATENTS 2,581,645 1/1952 Frieder et al.244-149 2,996,989 8/1961 Grandy 102-70 3,362,664 l/1968 McElroy 244-138FOREIGN PATENTS 819,696 9/1959 Great Britain.

MILTON BUCHLER, Primary Examiner.

RICHARD A. DORNON, Assistant Examiner.

